The human animal isn’t the only one affected by allergies. Like you, your adult dog can suffer from allergic reactions to any number of things—in the air, on his skin, and in his food. Allergies must be diagnosed and treated by your veterinarian, but first, you must know what to look for.
The most common signs and symptoms of allergies include:
The most common allergy symptoms in dogs are the skin reactions, regardless of the cause. And they can they can crop up at any age. Just because he didn’t have allergies as a puppy, doesn’t mean your dog won’t have them now that he’s an adult. Inhalant, food, contact, and flea allergies are four of the most common types of allergies that might affect your dog.
Inhalant allergies in dogs are caused by the same common allergens that affect you—dust, grass, trees, mold, pollen, ragweed, etc. They can be seasonal or persistent and, while some breeds (especially short-snouted breeds) might experience the same sniffly, sneezy symptoms you might suffer, skin reactions are most common. Inhalant allergies often can be treated with the same medications you take, but please don’t treat your dog’s allergies without veterinary supervision.
Food allergies can be the most difficult to diagnose and manage. Treatment involves a hit-and-miss approach involving a restricted diet and the gradual reintroduction of possible allergens to determine the culprit. Skin reactions to food allergies are common in dogs, but frequent vomiting or diarrhea also can be a sign. Keep in mind that if there is a change in your dog’s diet (or he just ate something he wasn’t supposed to), he might experience an episode of vomiting or diarrhea, but this doesn’t necessarily mean your dog has an allergy. Watch and see if it becomes a persistent problem before scheduling a costly trip to the vet.
Contact and flea allergies generally cause skin irritation and are treated topically. You might be surprised to learn that most dogs are only vaguely bothered by fleas. But those that are allergic can suffer—and so can their owners. Dogs with contact and flea allergies often chew their skin raw, leading to hair loss, odor, and infection, so fastidious flea control is a must.
Allergies can vary from dog to dog, so it is important that you work with your vet to make sure your dog gets the best possible treatment. You’ll both be happier for it.

Providing pets with vitamins, minerals, and other nutritional components is important to pet health and well-being, and the best way to do this is to feed a high-quality, complete, and balanced diet. Supplementing dog food often upsets the balance and might cause health problems.
People supplement their dog's diet for different reasons:
It is important to know that a quality dog food is carefully formulated to meet the caloric needs of the animal. The food provides essential amino acids, vitamin-rich fish oils, and minerals specific to the nutritional requirements of the dog.
Quality foods are complete and balanced for a specific life stage or lifestyle. Adding table scraps or other supplements can disrupt the delicate nutrient balance.
The interaction between minerals is very complex. Fortunately, this area of nutrition has been the focus of extensive research for many years. Research has shown that not only are the individual levels of minerals in a diet important but the proper balance is also. An excess of one mineral might affect the absorption of a second, and lead to a deficiency in that second mineral.
One common way of supplementing is to feed extra meat. However, because meat contains 20 to 40 times more phosphorus than calcium, adding meat to a balanced diet will upset the calcium to phosphorus (or Ca:P) ratio, which is important for proper bone development and maintenance.
This might prompt your pet's body to absorb calcium from the bones in order to reach the right balance. This is often the case in older animals that experience tooth loss due to the reabsorption of bone from the lower jaw. Ca:P ratio should range between 1.1 to 1.4 parts of calcium for each part of phosphorus.
Excess amounts of calcium have been associated with several bone diseases affecting growing puppies. Owners of large-breed puppies, in particular, believe that their puppies require extra calcium for proper development of large bones. Adding yogurt, cottage cheese, or calcium tablets to the puppy's diet will only upset the body's delicate mineral balance.
Remember: Large-breed puppies consume more food and get the calcium their bodies need by eating the recommended portions. The best way to support a normal growth rate is to feed growing dogs a balanced diet using a portion-controlled regimen.
The Association of American Feed Control Officials (AAFCO) regulates the pet food industry and has established certain nutritional requirements for dogs. These requirements are published annually in the AAFCO Manual. Only pet foods that have met the strict criteria established by AAFCO can carry the 'complete and balanced' statement on the label.